This paper investigates very early‑age hydration monitoring of self‑compacting concrete (SCC) containing fly ash replacement ratios (0%, 15%, 30%, 45%, 60%) using embedded piezoelectric (PZT) sensors and electromechanical impedance (EMI) signatures. The authors apply principal component analysis (PCA) to the EMI conductance signatures to extract indices that reflect the liquid to solid transition during hydration (~1.5 h elongation with increasing fly ash). The PCA‑based indices show higher robustness and sensitivity compared to conventional penetration resistance tests and simpler EMI indices. The study demonstrates that embedded PZT sensors with advanced signal processing can quantitatively monitor early hydration and provide insight into setting and strength‑development processes.
The findings underline that early‑age hydration (rather than just maturity or temperature history) can be captured by embedded sensors and statistical signal analysis, offering the potential for very early decision‑making in construction. The authors suggest these methods help in understanding the micro‑mechanics of hydration and may aid in innovative quality control processes for modern concretes with SCMs (supplementary cementitious materials).
While the study using PZT sensors focuses on early hydration monitoring using piezoelectric impedance sensing and principal component analysis (PCA) to track the setting phase of concrete, Concurex offers a more direct, continuous measurement of hydration and strength via embedded electrical resistance sensors. The Concurex system does not rely on the complex signal processing associated with PCA, which may be prone to errors or require higher calibration. Additionally, while the PZT‑based approach excels at capturing hydration behavior, Concurex enhances its application by offering real-time structural decision-making capabilities, such as accurately predicting the strength development curve for the entire structure, not just isolated concrete samples. Furthermore, Concurex supports non-destructive testing of the entire slab and ensures structural integrity throughout the curing process, making it more suitable for use in real-world construction projects, where multi-faceted decisions must be made.
Kim Q., Mu Y., Li X., Wu X., Ren X. “A PCA‑Based Approach for Very Early‑Age Hydration Monitoring of Self‑Compacting Concrete Using Embedded PZT Sensors.” Sensors (Basel), Vol. 23(7): 3627 (2023).
